Matched-field localization of explosive sources in the Barents Sea using a horizontal array

Matched-field processing (MFP) techniques are used to estimate the range to explosive sources using acoustic data recorded on a bottom mounted horizontal array. Data from an experiment conducted by FFI in the Barents Sea in August of 1999 is used. The experiment took place in a relatively flat area (water depths 280-340 m), using broadband explosive (SUS) sources and a receiving array deployed in a vertical-horizontal (L-shaped) configuration. A two-step method is employed. The first step (environment focusing) makes use of a genetic algorithm global search method (SAGA) to determine an optimal seabed model for the area. The second step (localization) employs a normal mode acoustic propagation model (C-SNAP) in an exhaustive range-depth grid search for the source position, using the model environment obtained in the first step and an optimal equivalent water depth. Matching is performed using the incoherent broadband Bartlett processor. Good localization in range and depth is demonstrated when using data from two 10 Hz wide frequency bands within 40 Hz to 110 Hz, with source positions determined to within 300 m in range and 6 m in depth for sources to ranges 20 km from the array.